Study On The Wave Run-Up Of Stepped Seawall On Base Of Mass Source Generation Method Numerical Simulation

In recent years, with the development of society, people require higher and higher in coastal landscape. So they require reducing the height of the seawall as far as possible, and hope that the seawall type tend to have a gentle slope in the design, which will improve the affinity of the oceans to the visitors. However, reducing the height of seawall crest will causes wave overtopping. So, in order to effectively reduce the height of seawall, taking certain measures of wave dissipation to reduce the wave run-up is necessary. The stepped seawall, as a kind of special structure of sloping seawall, has a good wave absorbing effect, and its design conform with people increasingly awakening in landscape environmental protection consciousness, because of its hydrophilic gentle slope type can meet the demand of hydrophilic coastal recreational space planning. At present, although there are many stepped seawalls established in coastal areas, but there is few research on the influence law of wave run-up. Based on this, this paper used mass source generation wave method to study the wave run-up of stepped seawall for the first time, and completed the following several aspects of research work:This paper firstly introduced the role of the seawall, the importance of researching in the stepped seawalls wave run-up and the research progress of the hot topic of wave run-up in recent years at home and abroad. On that premise, this paper based on computational fluid dynamics software FLUENT, through its UDF interface, used C language program to compile second order Stokes wave mass source function expressions, finally achieved generating the quality of the source wave and the porous medium wave absorbing. the results showed that using mass source wave method can ensure the quality of the numerical flume wave field in the work place, and the waveform was stable, repeatability is good, wavelength is stable and could lasted long time.On that basis, this paper established numerical wave flume model which was similar to the physical model test to simulate wave run-up process of stepped seawalls, and verified the correctness of using mass source wave method to establish the numerical wave flume to simulate the wave run-up of stepped seawalls through the comparison wave run-up between simulation values and physical test values.Finally, different conditions and different stepped seawall structure schemes are simulated to research the wave run-up, and systematically analyzed wave run-up law of stepped seawall impacted by the factors of the water depth in front of the dike, seawall slope, height of the steps and the wave smoothness. The results show that:(1) In the selection range of water depth in front of the dike in this paper, under different conditions of outside slope, the wave run-up R of stepped seawalls was gradually reduced with the increase of water depth in front of the dike d, and was a linear change to water depth in front of the dike. When the ratio of water depth in front of the dike and wave steepness d/L is equal to 0.133～0.6, the wave run-up R decrease with the increase of d/L. And when d/L=0.133～0.3, d/L had a strong impact on the wave run-up R When the d/L> 0.3, the impact of d/L on the wave run-up R became weak. (2) As the flat seawalls, the wave run-up R of stepped sea walls showed a trend of increasing firstly and diminishing afterward with the slope turning slow. However, the crest value of stepped seawalls wave run-up appeared in a steeper slope relative to plat seawalls. And the stepped seawalls has a obvious reduction effect in wave run-up relative to plane slope seawalls, but as the seawall slope turning slow, the reduction effect tends to weak. (3) Under the same condition of seawall slope and wave smoothness, the wave run-up has a trend of diminishing firstly and increasing afterward with the seawall bench height increasing. (4) When the seawall slope is well steep, there appeared standing wave before the seawall, and the wave run-up decreased with the increasing wave smoothness; As seawall slope turned slow, there appeared shock wave and plunging wave form before the seawall, and the wave run-up increased with the increasing wave smoothness.